1. Field of the Invention
The present invention generally relates to intravascular devices for treating certain medical conditions and, more particularly, relates to intravascular occlusion devices for selective occlusion of a vessel anywhere in the body's circulatory system where it is desired to stop the flow of blood. The devices made in accordance with the invention are particularly well suited for delivery through a catheter or the like to a remote location in a patient's vascular system within a patient's body whereby a passageway to be occluded, has an axis and at least one aperture which intersects another vessel wall somewhat perpendicular to the axis.
2. Description of the Related Art
A wide variety of intravascular devices are used in various medical procedures. Certain intravascular devices, such as catheters and guidewires, are generally used simply to deliver fluids or other medical devices to specific locations within a patient's body, such as a selective site within the vascular system. Other, frequently more complex, devices are used in treating specific conditions, such as devices used in removing vascular occlusions or for treating septal defects and the like.
In certain circumstances, it may be necessary to occlude a patient's vessel, chamber, channel, hole or cavity such as to stop blood flow there through.
Mechanical embolization devices are well known in the art and sold commercially for occlusion of vessels in various locations within the vasculature. U.S. Pat. No. 6,123,715 by Amplatz and U.S. Pat. No. 5,725,552 by Kotula disclose intravascular occlusion devices fabricated from Nitinol braided metal fabric which are heat-set in molds to an expanded shape, but which can be compressed for delivery through a catheter to a treatment site, whereby the device, when urged out of the delivery catheter, self expands within the vasculature to occlude blood flow at the treatment site. The details of the various designs and configurations, as well as methods of fabricating and using the devices, are detailed in the aforementioned patents and incorporated in total herein by reference.
Although the occlusion devices described by Amplatz and Kotula patents are quite effective, there are significant improvements that can be made. In the Amplatz U.S. Pat. No. 5,725,552, there are described, in FIGS. 6A-C, and 11-18, two occlusion devices, each of which incorporates disk elements at one or both ends. The devices further incorporate a cylindrical portion with a diameter smaller than the disk maximum diameter and extending with an axis generally perpendicular to the plane of the disk. An example of this prior art is shown in FIGS. 1A, 1B and 2 hereof. The mentioned prior art devices do not always align themselves as well as possible to the anatomical conditions due to the lack of bending flexibility between the cylindrical portion and the disk portion. This occurs when the vessel wall containing the aperture of the vessel to be occluded is not quite perpendicular to the axis of the vessel to be occluded. In the case of double disked occluders for use, for example, in Ventricular Septal Defects (VSD), Atrial Septal Defects (ASD) and Patent Foraman Ovale (PFO) and the like, it may be that neither wall is perpendicular to the passageway or aperture to be occluded. When this occurs, with the prior art devices, the disk attempts to align, but it's lack of flexibility causes portions of the disk to extend further from the vessel wall than desired which may interfere with blood flow or cause gaps between portions of the disk and the vessel wall.
The prior art devices represented by the Amplatz and Kotula patents, with a single disk, are retained in place, as deployed, by sizing the cylindrical portion diameter larger in its unrestrained self expanding condition larger than the diameter of the vessel to be occluded. This imparts a load from the Nitinol braid's desire to expand larger to be imparted against the body lumen tissue to secure the device in place. Due to lack of precision in estimating the diameter of the vessel to be occluded or the body's ability to yield or dilate in response to pressure changes, and movement of the body, the retention force can occasionally be insufficient to retain the device in place as desired.
Accordingly, it would be advantageous to provide an improved occlusion device which offers increased flexibility between the disk and the cylindrical diameter for better disk alignment to the aperture wall and also to improve the retention of the device, particularly in a single disk occluder device.